Clinical applications of IL-2.

Several years of clinical trials with IL-2, including modifications of dose and schedule and combinations with other biologic agents or chemotherapy, have shown much more limited anticancer activity for this agent than was anticipated from the preclinical studies. Even for its FDA-approved indication (metastatic renal cell carcinoma patients with good performance status), IL-2 probably benefits only a small subset of patients, and no prognostic factors have yet been identified to pinpoint these patients. In addition, clinical activity in patients with renal cell carcinoma treated with high-dose IL-2 is achieved at the expense of substantial acute toxicity. Nonetheless, the durable complete responses observed in a small percentage of patients with metastatic renal cell carcinoma and metastatic melanoma, and the potent immunomodulatory effects of IL-2, suggest that it may yet become an important anticancer agent, perhaps in association with active and adoptive immunotherapy. The agent also has shown potential for the treatment of infectious diseases and immunodeficiency states.